Possibilities of hydrogen fluoride chemical lasers are both rather well known and quite frustrating. Atomic fluorine and molecular hydrogen react to form vibrationally excited HF, conventionally designated HF.sup.+.sup.+ and atomic hydrogen, represented by the reaction (conventionally designated the "cold" reaction): EQU F + H.sub.2 .fwdarw. HF.sup.+.sup.+ + H
Atomic hydrogen and molecular fluorine react to form vibrationally excited HF and atomic fluorine (conventionally designated the "hot" reaction: EQU H + F.sub.2 .fwdarw. HF.sup.+.sup.+ + F
In either case, the vibrational energy of HF.sup.+.sup.+ is a potential source of laser emission. The HF vibrational energy production in the cold reaction is considerably less than in the hot reaction.
To produce continuous working (CW) hydrogen fluoride lasers it has been the practice to employ the cold reaction, using hydrogen and dissociated fluorine. The efficiency for laser systems employing simultaneously both reactions, conventionally designated the chain reactions, is much less than systems utilizing only the cold reaction. However, based on the available vibrational energy, a laser system using the chain reactions can be several times more efficient, but an effective practical device has never been produced to utilize this result.
The present invention relates to a CW laser system in which the mixing of the two flows and the extraction of laser power are in separate regions. Mixing is carried out at greatly reduced temperatures such as about 100.degree.K, and power is extracted at a later point after shock has resulted in increased temperature.
While it has not heretofore been possible to produce efficient CW laser emission using the energy available from the chain reactions, pulsed lasers utilizing the chain reaction, on the other hand, have been operable. For such pulsed lasers, the two chemicals hydrogen and fluorine, are mixed, usually in a buffer such as a noble gas, for example, helium, argon or the like, and are pulsed or triggered by suitable external initiation such as ultraviolet radiation.
Reactions with hydrogen and deuterium are for most purposes identical but because of the atomic difference some corresponding differences in result can be observed. In the case of lasers, for example, it is observed the emitted radiation from DF is significantly lower frequency than for HF, DF emission experiences less molecular absorption by the atmosphere. Accordingly, the present invention is disclosed with reference to hydrogen for purposes of simplicity, but it is to be understood that deuterium is the presently preferred form where transmission through air is important.